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The epsilon4 allele of the apolipoprotein E gene (APOE) is associated with increased risk and earlier age at onset in late onset Alzheimer's disease (AD). Other factors, such as expression level of apolipoprotein E protein (apoE), have been postulated to modify the APOE related risk of developing AD. Multiple loci in and outside of APOE are associated with a high risk of AD. The aim of this exploratory hypothesis generating investigation was to determine if some of these loci predict cerebrospinal fluid (CSF) apoE levels in healthy non-demented subjects. CSF apoE levels were measured from healthy non-demented subjects 21-87 years of age (n=134). Backward regression models were used to evaluate the influence of 21 SNPs, within and surrounding APOE, on CSF apoE levels while taking into account age, gender, APOE epsilon4 and correlation between SNPs (linkage disequilibrium). APOE epsilon4 genotype does not predict CSF apoE levels. Three SNPs within the TOMM40 gene, one APOE promoter SNP and two SNPs within distal APOE enhancer elements (ME1 and BCR) predict CSF apoE levels. Further investigation of the genetic influence of these loci on apoE expression levels in the central nervous system is likely to provide new insight into apoE regulation as well as AD pathogenesis. [ABSTRACT FROM AUTHOR]

Corpus callosum area has been examined in neurodegenerative diseases as a marker for cortical pathology and for differential diagnosis; however, it has not been examined in Parkinson's disease (PD). We compared callosal area in patients with PD and PD with dementia (PDD) to healthy controls and patients with Alzheimer's disease (AD). We subsequently compared our results to a meta-analysis of studies examining callosal area in AD, frontotemporal dementia (FTD), progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD). For the imaging study, midsagittal T1-weighted MRIs were analyzed and the callosal area was determined in patients with PD (n = 24), PDD (n = 25), AD (n = 16) and controls (n = 27). The meta-analysis combined results from all publications (Medline or PubMed) representing unique samples and measuring callosal area in AD, FTD, PSP, and CBD. We found that PD and PDD patients did not show statistically significant callosal atrophy compared to controls (effect size d, 95% CI, d = 0.13, -0.26 to 0.52, and d = 0.05, -0.44 to 0.33, respectively) or AD. The AD patients had a significant loss of callosal area compared to controls (d = -0.58, -1.01 to -0.15). Dementia severity was correlated with total callosal atrophy in AD (R = 0.66, p < 0.01) but not in PDD patients (R = 0.18, p > 0.1). The meta-analysis revealed significant combined effect sizes for callosal atrophy of: AD (d = -1.03, -1.13 to -0.93), FTD (d = -1.21, -1.56 to -0.86), PSP (d = -1.09, -1.38 to -0.81), and CBD (d = -1.80, -2.18 to -1.43). We conclude that PD and PDD patients do not have callosal atrophy in contrast to other neurodegenerative diseases, including AD. Callosal atrophy was correlated with dementia severity in patients with AD but not PDD. [ABSTRACT FROM AUTHOR]